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Full Discussion: Use of colon
Top Forums Shell Programming and Scripting Use of colon Post 302916389 by Rameshck on Tuesday 9th of September 2014 04:27:07 PM
Old 09-09-2014
Use of colon

There was a sample code on forum I found sometime back:

Code:
$ f() { local foo=; : ${foo=unset}; declare -p foo; }; f
declare -- foo=""

$ f() { local foo; : ${foo=unset}; declare -p foo; }; f
declare -- foo="unset"

Can someone explain why was colon (:) is being used here. Whats its use?

Last edited by Don Cragun; 09-09-2014 at 05:45 PM.. Reason: Disable smilies in this posting.
 

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PPI::Statement::Variable(3)				User Contributed Perl Documentation			       PPI::Statement::Variable(3)

NAME
PPI::Statement::Variable - Variable declaration statements SYNOPSIS
# All of the following are variable declarations my $foo = 1; my ($foo, $bar) = (1, 2); our $foo = 1; local $foo; local $foo = 1; LABEL: my $foo = 1; INHERITANCE
PPI::Statement::Variable isa PPI::Statement::Expression isa PPI::Statement isa PPI::Node isa PPI::Element DESCRIPTION
The main intent of the "PPI::Statement::Variable" class is to describe simple statements that explicitly declare new local or global variables. Note that this does not make it exclusively the only place where variables are defined, and later on you should expect that the "variables" method will migrate deeper down the tree to either PPI::Statement or PPI::Node to recognise this fact, but for now it stays here. METHODS
type The "type" method checks and returns the declaration type of the statement, which will be one of 'my', 'local', 'our', or 'state'. Returns a string of the type, or "undef" if the type cannot be detected (which is probably a bug). variables As for several other PDOM Element types that can declare variables, the "variables" method returns a list of the canonical forms of the variables defined by the statement. Returns a list of the canonical string forms of variables, or the null list if it is unable to find any variables. symbols Returns a list of the variables defined by the statement, as PPI::Token::Symbols. TO DO
- Write unit tests for this SUPPORT
See the support section in the main module. AUTHOR
Adam Kennedy <adamk@cpan.org> COPYRIGHT
Copyright 2001 - 2011 Adam Kennedy. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of the license can be found in the LICENSE file included with this module. perl v5.16.2 2011-02-25 PPI::Statement::Variable(3)
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